Method and apparatus for configuring devices to enable determination of location information

ABSTRACT

Aspects of the subject disclosure may include, for example, determining, according to a location of each of a plurality of devices, an arrangement of coverage areas of devices pairs of the plurality of devices to enable a determination of a mobile device location relative to one or more of the devices pairs within a demarcated area, and identifying a transmission schedule for each of the devices pairs to transmit a wireless signal that initiates a process to determine the mobile device location. Other embodiments are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/938,041, filed on Jul. 24, 2020, which claims the benefit of priorityto U.S. Provisional Application Ser. No. 62/878,128, filed on Jul. 24,2019. The contents of each of the foregoing are hereby incorporated byreference into this application as if set forth herein in full.

FIELD OF THE DISCLOSURE

The subject disclosure relates to a method and apparatus for configuringdevices to enable determination of location information.

BACKGROUND

Determining location information between objects can serve multiplepurposes such as predicting and mitigating collisions between objects,tracking distances between objects, enforcing distancing betweenobjects, inventory management, or combinations thereof. Objects caninclude people, mobile machinery such as forklifts and robots, vehiclescontrolled by individuals or driverless, or other objects for whichlocation management and/or tracking may be desirable. Locationinformation can correspond to distances between objects, trajectory ofobjects, speed of objects, positions of objects, or combinationsthereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the accompanying drawings, which are notnecessarily drawn to scale, and wherein:

FIG. 1 is a block diagram illustrating an exemplary, non-limitingembodiment of a mobile tag and anchors for determining locationinformation between the mobile tag and the anchors in accordance withvarious aspects described herein.

FIG. 2 is a block diagram illustrating an exemplary, non-limitingembodiment of a timing diagram for determining location informationbetween the mobile tag and the anchors of FIG. 1 in accordance withvarious aspects described herein.

FIG. 3 is a block diagram illustrating an exemplary, non-limitingembodiment for determining location information between the mobile tagand pairs of anchors in accordance with various aspects describedherein.

FIGS. 4A, 4B and 4C are block diagrams illustrating exemplary,non-limiting embodiments for selecting pairs of anchors in accordancewith various aspects described herein.

FIG. 5 is a block diagram illustrating an exemplary, non-limitingembodiment of a mobile tag and an anchor for determining locationinformation between the mobile tag and the anchor in accordance withvarious aspects described herein.

FIG. 6 is a block diagram illustrating an exemplary, non-limitingembodiment of a timing diagram for determining location informationbetween the mobile tag and the anchor of FIG. 5 in accordance withvarious aspects described herein.

FIG. 7 is a block diagram illustrating an exemplary, non-limitingembodiment for determining location information of mobile tags in ademarcated area in accordance with various aspects described herein.

FIG. 8 depicts an illustrative embodiment of a method for determininglocation information and uses thereof in accordance with various aspectsdescribed herein.

FIG. 9 is a block diagram illustrating an exemplary, non-limitingembodiment for scheduling a process for determining location informationbetween mobile tags and pairs of anchors in the demarcated area of FIG.7 in accordance with various aspects described herein.

FIG. 10 is a block diagram of an example, non-limiting embodiments of acommunication device in accordance with various aspects describedherein.

FIG. 11 is a block diagram of an example, non-limiting embodiments of acomputing system in accordance with various aspects described herein.

DETAILED DESCRIPTION

The subject disclosure describes, among other things, illustrativeembodiments for determining location information between a mobile tagand one or more anchors. Other embodiments are described in the subjectdisclosure.

FIG. 1 is a block diagram illustrating an exemplary, non-limitingembodiment of a mobile tag 101 and anchors 102 (“A”) and 104 (“B”) fordetermining location information between the mobile tag 101 (“M”) andthe anchors 102 and 104 in accordance with various aspects describedherein. In an embodiment, anchor 102 can be configured to transmit afirst wireless signal (s₁) that can be received by anchor 104 and themobile tag 101. The timing of transmission by anchor 102 and receptionby the mobile tag 101 and anchor 104 of the first wireless signal (s₁)is depicted in FIG. 2 .

In an embodiment, anchor 102 transmits the first wireless signal (s₁) attime t₀, which in turn is received by the mobile tag 101 at time t₁ andanchor 104 at time t₂. Anchor 104 can be configured to transmit a secondwireless signal (s₂) at time t₃, which is received by the mobile tag 101at time t₄. The mobile tag 101 can be configured to use a timedifference of arrival (TDOA) measurement technique based on the firstand second wireless signals (s₁, s₂) to determine location informationbetween the mobile tag 101 and the anchors 102 and 104 as will bedescribed below.

In an embodiment, anchors 102 and 104 are stationary. Accordingly, theirx-y coordinates and the distance between anchors 102 and 104 (d_(AB))can be made known to the mobile tag 101 either by a look-up tableprovisioned into a memory of the mobile tag 101 or by including suchinformation in the first wireless signal (s₁), which can then beobtained by the mobile tag 101. Additionally, the mobile tag 101 can beconfigured to include in its look-up table the receive time and transmittime (t₂, t₃) of anchor 104 and/or a time difference between these times(Δt=t₃−t₂), or can receive this information in the second wirelesssignal (s₂) transmitted by anchor 104. The equations that follow can beused to calculate a first possible location of the mobile tag 101relative to anchor pairs 102, 104.

The distance between anchor 102 and the mobile tag can be representedas,d _(AM) =c(t ₁ −t ₀)  (EQ 1),where c is the speed of light constant. Similarly, the distance fromanchor 102 to anchor 104 can be represented as,

$\begin{matrix}{d_{AB} = {{c\left( {t_{2} - t_{0}} \right)}.}} & \left( {{EQ}\mspace{14mu} 2} \right)\end{matrix}$Additionally, the distance from anchor 104 to the mobile tag 101 can berepresented as,

$\begin{matrix}{d_{BM} = {{c\left( {t_{4} - t_{3}} \right)}.}} & \left( {{EQ}\mspace{14mu} 3} \right)\end{matrix}$The total distance traveled by the first wireless signal (s₁) fromanchor 102 to anchor 104 and the second wireless signals (s₂) fromanchor 104 to mobile tag 101 can be represented as,d _(AB) +d _(BM) =c(t ₂ −t ₀ +t ₄ −t ₃)  (EQ 4A).To eliminate variable t₀, equation EQ1 can be subtracted from equationEQ 4A, resulting in,d _(AB) +d _(BM) −d _(AM) =c(t ₂ −t ₁ +t ₄ −t ₃)  (EQ 4B).Substituting Δt=t₃−t₂ into EQ 4B results in equation,d _(AB) +d _(BM) −d _(AM) =c(t ₄ −t ₁ −Δt)  (EQ 4C).

Since d_(AB) is a constant known to the mobile tag 101 and the timevariables of the factor c(t₄−t₁−Δt) are also known to the mobile tag101, EQ 4C can be rewritten as,d _(BM) −d _(AM) =Δd ₁  (EQ 5),where Δd₁=c(t₄−t₁−Δt)−d_(AB), which are constants known to mobile tag101. Furthermore, in an example of two-dimensional (2D) space, thedistance between anchor 102 and the mobile tag 101 can be representedas,

${d_{AM} = \sqrt{\left( {x - x_{1}} \right)^{2} + \left( {y - y_{1}} \right)^{2}}},$

and the distance between anchor 104 and the mobile tag 101 can berepresented as,

$d_{BM} = {\sqrt{\left( {x - x_{2}} \right)^{2} + \left( {y - y_{2}} \right)^{2}}.}$Substituting d_(AM) and d_(BM) in EQ 5 results in the followingequation,√{square root over ((x−x ₂)²+(y−y ₂)²)}−√{square root over ((x−x₁)²+(y−y ₁)²)}=Δd ₁  (EQ 6).

Equation EQ 6 has only two unknown variables (x, y) that can be solvedby the mobile tag 101 utilizing a non-linear regression technique (e.g.,Nonlinear Least Squares). Such a technique produces a hyperbolic curveof solutions for x and y that is associated with the positions ofanchors pairs 102, 104. Such a hyperbolic curve can be represented as,h _(AB) =Δd ₁  (EQ 7A),where h_(AB)=√{square root over ((x−x₂)²+(y−y₂)²)}−√{square root over((x−x₁)²+(y−y₁)²)}. The mobile tag 101 can be further configured toperform the above calculation across other anchor pairs as depicted inFIG. 3 . For example, the mobile tag 101 can be configured to determinea hyperbolic curve between anchors 102 and 106 (i.e., anchors A and C)resulting in equation,h _(AC) =Δd ₂  (EQ 7B),where Δd₂ is a constant known to mobile tag 101, and whereh_(AC)=√{square root over ((x−x₃)²+(y−y₃)²)}−√{square root over((x−x₁)²+(y−y₁)²)}. Additionally, the mobile tag 101 can be configuredto determine a hyperbolic curve between anchors 106 and 108 (i.e.,anchors C and D) resulting in equation,h _(CD) =Δd ₃  (EQ 7C),where Δd₃ is a constant known to mobile tag 101, and whereh_(CD)=√{square root over ((x−x₄)²+(y−y₄)²)}−√{square root over((x−x₃)²+(y−y₃)²)}. The intersection 109 of hyperbolic curves h_(AB),h_(AC) and h_(CD) corresponding to equations EQ 7A-7C can provide atwo-dimensional coordinate location (i.e., x, y) for the mobile tag 101relative to anchors pairs 102 and 104 (anchors A/B), 106 and 108(anchors A/C), 106 and 108 (anchors C/D). It will be appreciated thatthe mobile tag 101 can also be configured to determine athree-dimensional coordinate (i.e., x, y, z) of its location byutilizing a fourth pair of anchors.

To enable the above calculations, the pairs of anchors utilized by themobile tag 101 must satisfy a coverage area that encompasses the anchorpairs and the mobile tag 101. For example, referring to FIG. 4A, thecoverage area of anchor 102 (anchor “A”) is defined by reference 110,while the coverage area of anchor 104 (anchor “B”) is defined byreference 112. The overlapping region 114 represents the coverage areathat is jointly shared by anchors 102 and 104. Since anchor 104 and themobile tag 101 must be able to receive the first wireless signal (s₁)generated by anchor 102, anchors 104 and the mobile tag 101 must belocated in the overlapping region 114. Additionally, the mobile tag 101must be in the overlapping region 114 in order to receive the secondwireless signal (s₂) generated by anchor 104. Conditions such asdescribed above for anchor pairs 102, 104 (anchors A/B) must also besatisfied by the other anchor pairs 102, 106 (anchors A/C) and anchorpairs 106, 108 (anchors C/D) in order to enable the mobile tag 101 toperform the triangulation calculations described above for hyperboliccurves h_(AB), h_(AC) and h_(CD).

FIG. 4B shows that the coverage areas 110 and 116 of anchor pairs 102,106 (anchors A/C), respectively, creates an overlapping region 120 thatencompasses anchors 102 and 106 and the mobile tag 101, thereby enablingthe mobile tag 101 to calculate hyperbolic curve h_(AC). Additionally,FIG. 4C shows that the coverage areas 122 and 124 of anchor pairs 106,108 (anchors C/D), respectively, creates an overlapping region 126 thatencompasses anchors 106 and 108 and the mobile tag 101, thereby enablingthe mobile tag 101 to calculate hyperbolic curve h_(CD).

FIG. 5 depicts another embodiment for determining location informationbetween the mobile tag 101 and an anchor 102. In this embodiment, themobile tag 101 can be configured to use a two-way time of arrival(TW-TOA) process for determining a distance between itself and theanchor 102. Optionally, the process may begin at anchor 102 whichtransmits a first wireless signal (s₁), which is received at time t₁.Wireless signal (s₁) can include the x-y coordinates (x₁, y₁) of anchor102. Upon receiving the first wireless signal (s₁), the mobile tag 101can be configured to transmit a second wireless signal (s₂), which canrepresent a range request (R-REQ) signal directed to anchor 102initiated at time t₂ and received by anchor 102 at time t₃.

Upon receiving the R-REQ signal at time t₃, the anchor 102 can processthe R-REQ signal and initiate at time Li a transmission of a thirdwireless signal (s₃) representing a range response (R-RSP) signal thatis received by the mobile tag 101 at time t₅. The time to process theR-REQ signal and transmit the R-RSP signal can be represented byΔt=t₄−t₃, which can be communicated to the mobile tag 101 via the thirdwireless signal (s₃).

The mobile tag 101 can be configured to determine a roundtrip distancebased on the formula,d _(r-trip) =d _(AM) +d _(MA),where d_(r-trip) is the roundtrip distance from the mobile tag 101 toanchor 102 and back to mobile tag 101, d_(MA) is the distance from themobile tag 101 to anchor 102, and d_(AM) is the distance from anchor 102to the mobile tag 101. The distance from the mobile tag 101 to anchor102 can be determined by,d _(MA) =c(t ₃ −t ₂).Similarly, the distance from anchor 102 to the mobile tag 101 can bedetermined by,d _(AM) =c(t ₅ −t ₄).With the above equations, the roundtrip distance can be rewritten as,

d_(r − trip) = c(t₅ − t₄ + t₃ − t₂).

As noted earlier, the time to process the R-REQ signal and transmit theR-RSP signal via anchor 102 can be represented as Δt=t₄−t₃. Anchor 102can be configured to transmit the value of Δt in the R-RSP signal foruse by the mobile tag 101 in calculating d_(r-trip). Substituting Δt ind_(r-trip) results in the formula,d _(r-trip) =c(t ₅ −t ₂ −Δt).Since the values of t₅, t₂, and Δt are known to the mobile tag 101, themobile tag 101 can readily calculate d_(r-trip). The mobile tag 101 canalso calculate the distance from the mobile tag 101 to anchor 102 basedon the formula,

d_(MA) = d_(r − trip)/2.It will be appreciated that the mobile tag 101 can also be configured toknow a priori the fixed value of Δt thus eliminating the need totransmit the value of Δt in the R-RSP signal. This knowledge can bebased on a pre-provisioning of the mobile tag 101 with this informationprior to deployment. In yet another embodiment, the processing time toreceive the R-REQ signal and respond with the transmission of the R-RSPsignal can be a fixed processing time interval known and used by alldevices in a network performing TW-TOA analysis. It will be furtherappreciated that the R-REQ and the R-RSP signals can be transmittedusing ultra-wideband signaling technology to increase the accuracy ofthe d_(r-trip) calculations. Accordingly, the TW-TOA illustrated in FIG.5 can be used by either the mobile tag 101 or anchors in otherembodiments to calculate a relative distance between each other.

It will be appreciated that the TDOA and TW-TOA processes describedabove can also between mobile tags 101. For example, FIGS. 1-3, 4A-4C,and 5-6 can be adapted so that the anchors are replaced with mobile tags101. In this embodiment, mobile tags 101 can use TDOA or TW-TOA toobtain location information amongst each other based on the processesdescribed earlier for TDOA and TW-TOA, respectively.

It will be further appreciated that a mobile tag 101, depicted in FIGS.1, 3, 4A-4C, 5 , can be configured with multiple antennas and phasedetectors to calculate an angle of arrival of any wireless signalgenerated by an anchor and received by the mobile tag 101 based on aphase difference between the antennas determined from the receivedwireless signal. An angle of arrival calculation can be used todetermine an angular orientation between a mobile tag 101 and an anchor.It will be further appreciated that the mobile tags 101 can beconfigured to determine a speed of travel of the mobile tag 101 byperforming multiple location measurements over a time period. Withangular orientation and speed of travel, a mobile tag 101 can alsodetermine its trajectory of travel. Alternatively, the mobile tags 101can be configured with an orientation sensor (e.g., a magnetometer) todetermine an angular orientation with an anchor.

As will be discussed shortly, TDOA, TW-TOA, angular orientation, speedof travel, or combinations thereof can be utilized in an environmentsuch as illustrated in FIG. 7 .

FIG. 7 is a block diagram illustrating an exemplary, non-limitingembodiment for determining location information of mobile tags 201 in ademarcated area 200 in accordance with various aspects described herein.In the illustration of FIG. 7 , the demarcated area 200 can represent awarehouse with racks or shelves 206 for managing the distribution ofproducts and/or materials. It will be appreciated that the demarcatedarea 200 can correspond to numerous other use cases, including withoutlimitation, a parking lot for managing parking spots, a commercial orretail environment for monitoring individuals and/or assets, assistednavigation of vehicles and/or machinery such as robots or forklifts,collision detection and avoidance of objects, managing separationbetween objects and/or individuals, as well as other suitableapplications for which the subject disclosure can be applied to. Forillustration purposes only, the demarcated area 200 of FIG. 7 will beconsidered a warehouse with racks and/or shelves 206.

The measurement technique used by the mobile tags 201 to determinelocation information within the demarcated area 200 can depend on thelocation of the mobile tags 201 relative to other anchors 204 in thedemarcated area 200. For example, when a mobile tag 201 is located insections 212 (i.e., open spaces without shelving 206 and line-of-site topairs of anchors 204), the mobile tag 201 can be configured to performTDOA measurements among pairs of anchors 204 as described above inrelation to FIGS. 1, 2, 3, 4A, 4B, 4C. On the other hand, when themobile tag 201 is located in an aisle 203 between racks/shelves 206, themobile tag 201 can be configured to perform TW-TOA measurements amongone or more anchors 204 located in the aisle 203 as described above inrelation to FIGS. 5-6 .

Additionally, an aisle 203 can be configured with two or more anchors204. An aisle 203 can have more than two anchors 204 when the coveragearea of a first anchor 204 at one end of the aisle 203 has insufficientcoverage to reach a second anchor 204 at the other end of the aisle 203and vice-versa—see sections 220 and 224. However, when the coverage areaof a first anchor 204 at one end of the aisle 203 has sufficientcoverage to reach a second anchor 204 at the end of the aisle 203 andvice-versa, then no more than two anchors 204 is necessary in the aisle203—see region 222.

FIG. 8 depicts an illustrative embodiment of a method 300 in accordancewith various aspects described herein. Method 300 can begin at step 302where a computing system such as a server (described below in relationto FIG. 11 ) is configured to identify anchor pairs in the demarcatedarea 200 of FIG. 7 that provide sufficient coverage to enable TW-TOA orTDOA measurements depending on the location of the mobile tags 201.

In the case of open spaces, like region 212 (repeated in severalportions of the demarcated area 200 of FIG. 7 ), mobile tags 201 areconfigured to use TDOA measurement techniques to determine locationinformation. To enable TDOA measurements, the server is configured atstep 302 to identify, for a certain number of x-y coordinates obtainedfrom a digitization of an open space defined by region 212 where amobile tag 201 may be located, at least three pairs of anchors 204 thathave overlapping coverage that satisfy the condition described earlierin relation to FIGS. 3, 4A, 4B and 4C. It will be appreciated that othertechniques other than digitization of an open space can be used toidentify possible x-y coordinates used by the server to perform step302. In the case of spaces formed by aisles 203, like region 214(repeated in several portions of the demarcated area 200 of FIG. 7 ),mobile tags 201 are configured to use TW-TOA measurement techniques todetermine location information. To enable TW-TOA measurements, theserver is configured at step 302 to identify at least two anchors 204covering at least a portion of the aisle 203. The mobile tags 201 can beconfigured to perform TW-TOA with anchors 204 at opposite ends of anaisle 203 to provide further accuracy or at least validate locationinformation determined by the mobile tag 201. As noted earlier, pairs ofanchors 204 can be located at opposite ends of an aisle 203, or inbetween aisles 203 when a pair of anchors 204 is unable to cover for thefull-length of an aisle 203. The mobile tag 201 can be configured toperform TW-TOA measurement according to the embodiments described abovein relation to FIGS. 5-6 .

For open spaces such as region 212, a server can be configured at step302 to determine optimal pairs of anchors 204 in FIG. 7 that providesufficient coverage for any mobile tag 201 in the area such as region212 to perform triangulation with at least three pairs of anchors 204that satisfy the conditions set forth in FIGS. 4A-4C. The process ofselecting anchor pairs for TDOA triangulation and optimal coverage inopen spaces defined by region 212 can be performed as an iterativeanalysis by a server at step 302, or by other techniques that enableconvergence to a solution that provides coverage to mobile tags 201across most (if not all) open spaces depicted by region 212. In the caseof spaces defined by aisles 203, the server can identify the anchorpairs 204 in the aisles 203 that provide sufficient coverage to coverthe aisle from end-to-end as illustrated by sections 220-224 of FIG. 7 .

Once the anchor pairs 204 have been identified, the server can proceedto step 304 to identify a schedule for communications between anchorpairs 204 and one or more mobile tags 201. In one embodiment, theanchors 204 can be configured to transmit and receive wireless signalsin a single frequency band. A single frequency band for performing TDOAor TW-TOA measurements can reduce the design complexity of mobile tags201 and corresponding costs. To avoid collisions between anchor pairs204 transmitting in a same frequency band near other anchors, the servercan be configured to utilize a time-division scheme (timeslots) such asshown in FIG. 9 to enable anchor pairs 204 to communicate with eachother and with one or more mobile tags 201 without causing signalinterference (i.e., wireless collisions).

To achieve this, the server can be configured, for example, to determineat step 304 which anchor pairs 204 have overlapping coverage areas withother anchor pairs and schedule the communications between the anchorpairs and the mobile tags 201 during specific timeslots T₀-T_(n) (e.g.,402 a through 402 n). In the case where a pair of anchors 204 does nothave an overlapping coverage area with another anchor pair (e.g., anchorpairs at opposite ends of the demarcated area 200), the server canschedule simultaneous wireless communications of both anchor pairs 204during a same timeslot (not shown in FIG. 9 ). As part of the schedulingprocess shown in FIG. 9 , the server can be further configured at step304 to determine which of the anchor pairs 204 will initiate/start ameasurement session through a transmission of wireless signal (s₁). Suchanchors 204 will be referred to herein as source anchors 204.

In one embodiment, the anchor pairs 204 identified by the server at step302, and the transmission schedule and source anchors 204 determined bythe server at step 304 can be communicated to all anchors 204 viagateway anchors 208 communicatively coupled to the server. Gatewayanchors 204 can be located at the edges of the demarcated area 200 or inother locations of the demarcated area 200. Additionally, the server canalso be configured to share the identification of the anchor pairs 204and transmission schedules with the mobile tags 201. This informationcan be conveyed by gateway anchors 208 when the mobile tags 201 are inclose vicinity thereto, or by way of other anchors 204 which can beconfigured to obtain this information from the gateway anchors 208 andrelay the information to the mobile tags 201.

It will be appreciated that the locations of the anchors 204 in FIG. 7can be predefined before the implementation of step 302 by the server.That is, the anchors 204 can be placed by one or more individualsmanaging the placement of shelves/racks, etc. in the demarcated area200. The specific x-y coordinate locations of the anchors 204 can bedetermined by such individuals and communicated to the server via, forexample, a look-up table provided to the server, in order to performstep 302.

It will be further appreciated that in other embodiments, the locationof anchors can instead be determined by the server at step 302. In thisembodiment, the server can be provided with the location ofracks/shelves and/or other objects in the demarcated area 200 along withdimensions of the demarcated area 200 and dimensions of theracks/shelves and/or other objects. The server can then be configured toperform an iterative analysis to determine a location for anchors 204relative to the racks/shelves identified to the server that providedesirable coverage for mobile tags 201 to perform TDOA analysis in openspaces or TW-TOA analysis in aisles 203. In this embodiment, the servercan be configured to report the x-y coordinate locations of anchors 204to one or more personnel managing the floor space of the demarcated area200 for placement of the anchors 204 in their corresponding x-ycoordinate locations.

It will be further appreciated that once the anchors 204 have beenplaced in their designated locations determined by the server, theserver can be configured to provide the x-y coordinates to all anchors204 in the demarcated area 200 via gateway anchors 208 as describedabove. This information can also be conveyed by gateway anchors 208 whenthe mobile tags 201 are in close vicinity thereto, or by way of otheranchors 204 which can be configured to obtain this information from thegateway anchors 208 and relay the information to the mobile tags 201.

Referring back to FIG. 8 , at step 306, mobile tags 201 can beconfigured to initiate a process using TDOA or TW-TOA (and in someinstances angular orientation measurements) to obtain locationinformation depending on the location of the mobile tag 201 in thedemarcated area 200. In one or more embodiments (although othertechniques can be utilized) to assist mobile tags 201 in identifyingwhether they are in region 212 (i.e., open spaces) or region 214 (i.e.,aisles 203), the source anchors 204 can be configured to transmit in thefirst wireless signal (s₁) an indication whether to use TDOA or TW-TOA.The indication may be a flag or message that enables the mobile tag 201to determine whether it is in region 212 (an open space) or region 214(an aisle 203). The first wireless signal (s₁) can also convey to themobile tag 201 the x-y coordinates of one or both anchor pairs 204.Alternatively, the mobile tags 201 can be configured with a look-uptable that includes the x-y coordinates of all anchors 204 in thedemarcated area 200. The mobile tags 201 can obtain the lookup-tablefrom the server via the gateway anchors 208 or during provisioning ofthe mobile tag 201 by a user before the mobile tag 201 is deployed foruse in the demarcated area 200. It will be further appreciated that step306 can be adapted to enable mobile tags 101 to measure and therebyobtain location information between each other using TDOA or TW-TOA asdescribed earlier in relation to FIGS. 1-3, 4A-4C, and 5-6 .

Once a mobile tag 201 calculates location information via TDOA or TW-TOAmeasurement techniques, the mobile tag 201 can in turn report at step308 the location information to other devices such as other mobile tags201, the anchors 204 in its coverage area, and/or the server bycommunicating directly to one or more gateway anchors 208 or indirectlyvia one or more intermediate anchors 204 that can communicate with theone or more gateway anchors 208. The location information can includewithout limitation, x-y coordinates of the mobile tag 201 within thedemarcated area 200, a speed of travel of the mobile tag 201 determinedfrom multiple location measurements over a time period, a trajectory ofthe mobile tag 201, angular orientation of the mobile tag 201 relativeto other anchors 204 and/or other mobile tags 201, or any combinationsthereof. Since sharing location information does not require precisionmeasurements via ultra-wideband signals, the mobile tags 201 can beconfigured to share location information with other devices using lowerpower wireless signaling techniques such as Bluetooth®, ZigBee®, WiFi orother suitable wireless signaling protocols.

Sharing location information of the mobile tags 201 enables the serverand/or other devices such as the anchors 204 and other mobile tags 201to track at step 310 movement and location of the mobile tags 201 anddetect and perform mitigation procedures at step 312. For example,mobile tags 201 can be configured to detect issues such as proximityviolations and/or possible collisions between mobile tags 201 from thisshared information. Upon detecting such issues, the mobile tags 201 canbe configured to assert an alarm (audible and/or visual) and/or takefurther mitigation action such as slow down or otherwise disable avehicle (e.g., a forklift, robot, automobile, etc.) that may collidewith an individual carrying a mobile tag 201. The mobile tag 201 may beintegrated in an identification badge or embedded in a mobilecommunication device (e.g., mobile phone, tablet, etc.), clipped on ashirt, integrated into an article of clothing of the individual orotherwise carried by the individual via other suitable methods forcarrying the mobile tag 201.

It will be appreciated that method 300 can be adapted for otherembodiments contemplated by the subject disclosure. For example, at step306, a mobile tag 201 can be adapted to obtain location informationbased on a determination whether it is in an open space defined byregion 212 or an aisle 203 defined by region 214. A mobile tag 201, forexample, can receive wireless signals from both an anchor 204 in an openspace and an anchor 204 in an aisle 203. To determine whether to performa TDOA measurement or a TW-TOA measurement, the mobile tag 201 can beconfigured to obtain from its internal memory a history of locations inthe demarcated area 200 that are stored by the mobile tag 201 todetermine if the most recent location (or trajectory of the mobile tag201) places the mobile tag 201 in an open space, region 212, or aisle203, region 214.

If the mobile tag 201 determines it is likely in an open space, region212, it can proceed to perform TDOA analysis based on the wirelesssignals generated by anchor pairs 204 in the open space. Otherwise, ifthe mobile tag 201 determines it is likely in an aisle, region 214, itcan proceed to perform TW-TOA analysis based on the wireless signalsgenerated by anchor pairs 204 in the aisle 203. If the mobile tag 201 isunable to make a determination where it is likely located from a historyof locations, the mobile tag 201 can be configured to perform TDOAanalysis based on the wireless signals generated by anchor pairs 204 inthe open space and TW-TOA analysis based on the wireless signalsgenerated by anchor pairs 204 in the aisle 203. The mobile tag 201 canbe configured to compare the location determined from TDOA and thelocation determined from TW-TOA to the stored location history andthereby make a determination as to which location to choose that moreclosely mimics the location history of the mobile tag 201.

While for purposes of simplicity of explanation, the respectiveprocesses are shown and described as a series of blocks in FIG. 8 , itis to be understood and appreciated that the claimed subject matter isnot limited by the order of the blocks, as some blocks may occur indifferent orders and/or concurrently with other blocks from what isdepicted and described herein. Moreover, not all illustrated blocks maybe required to implement the methods described herein. For example,steps 308-312 can be optional.

FIG. 10 is a block diagram of an example, non-limiting embodiments of acommunication device 500 in accordance with various aspects describedherein. Communication device 500 can serve in whole or in part as anillustrative embodiment of a mobile tag 101 and an anchor 102, 104, 106,108, 204 as depicted in FIGS. 1-7 , and can be configured to performportions of method 300 of FIG. 8 .

In an embodiment, communication device 500 can comprise a first wirelesstransceivers 501, a user interface (UI) 504, a power supply 514, and aprocessing system 506 for managing operations of the communicationdevice 500. In another embodiment, communication device 500 can furtherinclude a second wireless transceiver 502, a motion sensor 518, and anorientation sensor 520. The first wireless transceiver 501 can beconfigured to support wideband wireless signals such as ultra-widebandsignals (e.g., 500 MHz) for performing precision measurements such asTDOA and TW-TOA as described above and can be further configured forexchanging messages (e.g., x-y coordinates, location flags, etc.).

The second wireless transceiver 502 can be configured to supportwireless access technologies such as Bluetooth®, ZigBee®, or WiFi(Bluetooth® and ZigBee® are trademarks registered by the Bluetooth®Special Interest Group and the ZigBee® Alliance, respectively). Thesecond wireless transceiver 502 can be utilized to conserve power andoffload messaging between communication devices by utilizing narrow bandsignals such as Bluetooth®, ZigBee®, or WiFi, instead of ultra-widebandsignals. One or both wireless transceivers 501, 502 can also be used forobtaining a strength indicator (RSSI). One or both wireless transceivers501, 502 can also be equipped with multiple antennas and one or morephase detectors to determine angle of arrival of wireless signals andthereby an orientation of the communication device 500 (e.g., mobile tag101) relative to another communication device 500 (e.g., anchor 204).

The UI 504 can include an input device 508 that provides at least one ofone or more depressible buttons, a tactile keypad, a touch-sensitivekeypad, or a navigation mechanism such as a roller ball, a joystick, ora navigation disk for manipulating operations of the communicationdevice 500. The input device 508 can be an integral part of a housingassembly of the communication device 500 or an independent deviceoperably coupled thereto by a tethered wireline interface (such as a USBcable) or a wireless interface supporting for example Bluetooth®. The UI504 can further include a presentation device 510. The presentationdevice 510 can include a vibrator to generate haptic feedback, an LED(Light Emitting Diode) configurable by the processing system 506 to emitone or more colors, and/or a monochrome or color LCD (Liquid CrystalDisplay) or OLED (Organic LED) display configurable by the processingsystem to present alphanumeric characters, icons or other displayableobjects.

The UI 504 can also include an audio system 512 that utilizes audiotechnology for conveying low volume audio (for proximity listening by auser) and/or high volume audio (for hands free operation). The audiosystem 512 can further include a microphone for receiving audiblesignals of an end user. The audio system 512 can also be used for voicerecognition applications. The UI 504 can further include an image sensor513 such as a charged coupled device (CCD) camera for capturing still ormoving images in a vicinity of the communication device 500. The cameracan be used for performing facial recognition and user ID recognitionthat can be combined with embodiments of the subject disclosure.

The power supply 514 can utilize common power management technologiessuch as replaceable and rechargeable batteries, supply regulationtechnologies, and/or charging system technologies for supplying energyto the components of the communication device 500 to facilitate portableapplications. Alternatively, or in combination, the charging system canutilize external power sources such as DC power supplied over a physicalinterface such as a USB port or other suitable tethering technologies.

The motion sensor 518 can utilize motion sensing technology such as anaccelerometer, a gyroscope, or other suitable motion sensing technologyto detect motion of the communication device 500 in three-dimensionalspace. The orientation sensor 520 can utilize orientation sensingtechnology such as a magnetometer to detect the orientation of thecommunication device 500 (in degrees, minutes, or other suitableorientation metrics). In some embodiments, the orientation sensor 520can replace a need for utilizing multiple antennas with the first and/orsecond wireless transceivers 501, 502 and a phase detector forperforming angle of arrival measurements. In other embodiments, thefunction of the orientation sensor 520 can be combined with an angle ofarrival measurement performed with multiple antennas with the firstand/or second wireless transceivers 501, 502 and a phase detector.

The processing system 506 can utilize computing technologies such as amicroprocessor, a digital signal processor (DSP), programmable gatearrays, application specific integrated circuits (ASICs), and/or a videoprocessor with associated storage memory such as Flash, ROM, RAM, SRAM,DRAM or other storage technologies for executing computer instructions,controlling, and processing data supplied by the aforementionedcomponents of the communication device 500.

Other components not shown in FIG. 10 can be used in one or moreembodiments of the subject disclosure. For instance, the communicationdevice 500 can include a reset button (not shown). The reset button canbe used to reset the controller 506 of the communication device 500. Inyet another embodiment, the communication device 500 can also include afactory default setting button positioned, for example, below a smallhole in a housing assembly of the communication device 500 to force thecommunication device 500 to re-establish factory settings.

The communication device 500 as described herein can operate with moreor less of the circuit components shown in FIG. 10 . These variantembodiments can be used in one or more embodiments of the subjectdisclosure.

FIG. 11 depicts an exemplary diagrammatic representation of a machine inthe form of a computing system 600 within which a set of instructions,when executed, may cause the machine to perform any one or more of themethods described above. One or more instances of the machine canoperate, for example, as the computing system referred to in method 300of FIG. 8 . In some embodiments, the machine may be connected (e.g.,using a network 626) to other machines. In a networked deployment, themachine may operate in the capacity of a server or a client user machinein a server-client user network environment, or as a peer machine in apeer-to-peer (or distributed) network environment.

The machine may comprise a server computer, a client user computer, apersonal computer (PC), a tablet, a smart phone, a laptop computer, adesktop computer, a control system, a network router, switch or bridge,or any machine capable of executing a set of instructions (sequential orotherwise) that specify actions to be taken by that machine. It will beunderstood that a communication device of the subject disclosureincludes broadly any electronic device that provides data communication.Further, while a single machine is illustrated, the term “machine” shallalso be taken to include any collection of machines (physical or virtualmachines) that individually or jointly execute a set (or multiple sets)of instructions to perform any one or more of the methods discussedherein.

The computer system 600 may include a processor (or controller) 602(e.g., a central processing unit (CPU)), a graphics processing unit(GPU, or both), a main memory 604 and a static memory 606, whichcommunicate with each other via a bus 608. The computer system 600 mayfurther include a display unit 610 (e.g., a liquid crystal display(LCD), a flat panel, or a solid state display). The computer system 600may include an input device 612 (e.g., a keyboard), a cursor controldevice 614 (e.g., a mouse), a disk drive unit 616, a signal generationdevice 618 (e.g., a speaker or remote control) and a network interfacedevice 620. In distributed environments, the embodiments described inthe subject disclosure can be adapted to utilize multiple display units610 controlled by two or more computer systems 600. In thisconfiguration, presentations described by the subject disclosure may inpart be shown in a first of the display units 610, while the remainingportion is presented in a second of the display units 610.

The disk drive unit 616 may include a tangible computer-readable storagemedium 622 on which is stored one or more sets of instructions (e.g.,software 624) embodying any one or more of the methods or functionsdescribed herein, including those methods illustrated above. Theinstructions 624 may also reside, completely or at least partially,within the main memory 604, the static memory 606, and/or within theprocessor 602 during execution thereof by the computer system 600. Themain memory 604 and the processor 602 also may constitute tangiblecomputer-readable storage media.

One or more aspects of the subject disclosure include a device thatutilizes a processing system including a processor and a memory thatstores executable instructions that, when executed by the processingsystem, facilitate performance of operations. The operations can includeidentifying a location for each of a plurality of anchors havingdistributed positions in a demarcated area, determining, according tothe location of each of the plurality of anchors, an arrangement ofcoverage areas of anchor pairs of the plurality of anchors that enablesa determination of a mobile device location relative to one or more ofthe anchor pairs within the demarcated area, and identifying atransmission schedule for each of the anchor pairs to transmit awireless signal that initiates a process to determine the mobile devicelocation.

One or more aspects of the subject disclosure include a machine-readablemedium comprising executable instructions that, when executed by aprocessing system including a processor, facilitate performance ofoperations. The operations can include determining, according to alocation of each of a plurality of anchors, an arrangement of coverageareas of anchor pairs of the plurality of anchors to enable adetermination of a mobile device location relative to one or more of theanchor pairs within a demarcated area, and identifying a transmissionschedule for each of the anchor pairs to transmit a wireless signal thatinitiates a process to determine the mobile device location.

One or more aspects of the subject disclosure include a method fordetermining, by a processing system including a processor, according toa location of each of a plurality of anchors, an arrangement of coverageareas of anchor pairs of the plurality of anchors that enables adetermination of a mobile device location relative to one or more of theanchor pairs within a demarcated area, and identifying, by theprocessing system, a transmission schedule for each of the anchor pairsthat at least reduces interference between wireless signals transmittedby the anchor pairs of the plurality of anchors, the wireless signalsprompting a process to determine the mobile device location of a mobiledevice located in a coverage area of the anchor pairs.

Dedicated hardware implementations including, but not limited to,application specific integrated circuits, programmable logic arrays andother hardware devices can likewise be constructed to implement themethods described herein. Application specific integrated circuits andprogrammable logic array can use downloadable instructions for executingstate machines and/or circuit configurations to implement embodiments ofthe subject disclosure. Applications that may include the apparatus andsystems of various embodiments broadly include a variety of electronicand computer systems. Some embodiments implement functions in two ormore specific interconnected hardware modules or devices with relatedcontrol and data signals communicated between and through the modules,or as portions of an application-specific integrated circuit. Thus, theexample system is applicable to software, firmware, and hardwareimplementations.

In accordance with various embodiments of the subject disclosure, theoperations or methods described herein are intended for operation assoftware programs or instructions running on or executed by a computerprocessor or other computing device, and which may include other formsof instructions manifested as a state machine implemented with logiccomponents in an application specific integrated circuit or fieldprogrammable gate array. Furthermore, software implementations (e.g.,software programs, instructions, etc.) including, but not limited to,distributed processing or component/object distributed processing,parallel processing, or virtual machine processing can also beconstructed to implement the methods described herein. Distributedprocessing environments can include multiple processors in a singlemachine, single processors in multiple machines, and/or multipleprocessors in multiple machines. It is further noted that a computingdevice such as a processor, a controller, a state machine or othersuitable device for executing instructions to perform operations ormethods may perform such operations directly or indirectly by way of oneor more intermediate devices directed by the computing device.

While the tangible computer-readable storage medium 522 is shown in anexample embodiment to be a single medium, the term “tangiblecomputer-readable storage medium” should be taken to include a singlemedium or multiple media (e.g., a centralized or distributed database,and/or associated caches and servers) that store the one or more sets ofinstructions. The term “tangible computer-readable storage medium” shallalso be taken to include any non-transitory medium that is capable ofstoring or encoding a set of instructions for execution by the machineand that cause the machine to perform any one or more of the methods ofthe subject disclosure. The term “non-transitory” as in a non-transitorycomputer-readable storage includes without limitation memories, drives,devices and anything tangible but not a signal per se.

The term “tangible computer-readable storage medium” shall accordinglybe taken to include, but not be limited to: solid-state memories such asa memory card or other package that houses one or more read-only(non-volatile) memories, random access memories, or other re-writable(volatile) memories, a magneto-optical or optical medium such as a diskor tape, or other tangible media which can be used to store information.Accordingly, the disclosure is considered to include any one or more ofa tangible computer-readable storage medium, as listed herein andincluding art-recognized equivalents and successor media, in which thesoftware implementations herein are stored.

Although the present specification describes components and functionsimplemented in the embodiments with reference to particular standardsand protocols, the disclosure is not limited to such standards andprotocols. Each of the standards for Internet and other packet switchednetwork transmission (e.g., TCP/IP, UDP/IP, HTML, HTTP) representexamples of the state of the art. Such standards are from time-to-timesuperseded by faster or more efficient equivalents having essentiallythe same functions. In one or more embodiments, information regardinguse of services can be generated including services being accessed,media consumption history, user preferences, and so forth. Thisinformation can be obtained by various methods including user input,detecting types of communications (e.g., video content vs. audiocontent), analysis of content streams, and so forth. The generating,obtaining and/or monitoring of this information can be responsive to anauthorization provided by the user. In one or more embodiments, ananalysis of data can be subject to authorization from user(s) associatedwith the data, such as an opt-in, an opt-out, acknowledgementrequirements, notifications, selective authorization based on types ofdata, and so forth.

The illustrations of embodiments described herein are intended toprovide a general understanding of the structure of various embodiments,and they are not intended to serve as a complete description of all theelements and features of apparatus and systems that might make use ofthe structures described herein. Many other embodiments will be apparentto those of skill in the art upon reviewing the above description. Theexemplary embodiments can include combinations of features and/or stepsfrom multiple embodiments. Other embodiments may be utilized and derivedtherefrom, such that structural and logical substitutions and changesmay be made without departing from the scope of this disclosure. Figuresare also merely representational and may not be drawn to scale. Certainproportions thereof may be exaggerated, while others may be minimized.Accordingly, the specification and drawings are to be regarded in anillustrative rather than a restrictive sense.

Although specific embodiments have been illustrated and describedherein, it should be appreciated that any arrangement which achieves thesame or similar purpose may be substituted for the embodiments describedor shown by the subject disclosure. The subject disclosure is intendedto cover any and all adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, can be used in the subject disclosure.For instance, one or more features from one or more embodiments can becombined with one or more features of one or more other embodiments. Inone or more embodiments, features that are positively recited can alsobe negatively recited and excluded from the embodiment with or withoutreplacement by another structural and/or functional feature. The stepsor functions described with respect to the embodiments of the subjectdisclosure can be performed in any order. The steps or functionsdescribed with respect to the embodiments of the subject disclosure canbe performed alone or in combination with other steps or functions ofthe subject disclosure, as well as from other embodiments or from othersteps that have not been described in the subject disclosure. Further,more than or less than all of the features described with respect to anembodiment can also be utilized.

Less than all of the steps or functions described with respect to theexemplary processes or methods can also be performed in one or more ofthe exemplary embodiments. Further, the use of numerical terms todescribe a device, component, step or function, such as first, second,third, and so forth, is not intended to describe an order or functionunless expressly stated so. The use of the terms first, second, thirdand so forth, is generally to distinguish between devices, components,steps or functions unless expressly stated otherwise. Additionally, oneor more devices or components described with respect to the exemplaryembodiments can facilitate one or more functions, where the facilitating(e.g., facilitating access or facilitating establishing a connection)can include less than every step needed to perform the function or caninclude all of the steps needed to perform the function.

The Abstract of the Disclosure is provided with the understanding thatit will not be used to interpret or limit the scope or meaning of theclaims. In addition, in the foregoing Detailed Description, it can beseen that various features are grouped together in a single embodimentfor the purpose of streamlining the disclosure. This method ofdisclosure is not to be interpreted as reflecting an intention that theclaimed embodiments require more features than are expressly recited ineach claim. Rather, as the following claims reflect, inventive subjectmatter lies in less than all features of a single disclosed embodiment.Thus the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separately claimedsubject matter.

What is claimed is:
 1. A device, comprising: a processing systemincluding a processor; and a memory that stores executable instructionsthat, when executed by the processing system, facilitate performance ofoperations, the operations comprising: determining a location for eachof a plurality of anchors having distributed positions in a demarcatedarea; determining anchor pairs from the plurality of anchors accordingto the location of each of the plurality of anchors, wherein each anchorpair of the anchor pairs has an overlapping coverage area, resulting inoverlapping coverage areas, and wherein the determining the anchor pairsenables a determination of a mobile device location for a mobile devicerelative to the anchor pairs within the demarcated area; andidentifying, based on the overlapping coverage areas of the anchorpairs, a transmission schedule for the anchor pairs to transmitrespective wireless signals for the determination of the mobile devicelocation, wherein certain wireless signals of the respective wirelesssignals each provides a respective identification of a measurementtechnique that the mobile device is to employ for that wireless signalfor determining the mobile device location, wherein the measurementtechnique comprises a time difference of arrival measurement techniquewhen an anchor corresponding to the respective identification is locatedin a first type of area within the demarcated area and a time of arrivalmeasurement technique when an anchor corresponding to the respectiveidentification is located in a different type of area within thedemarcated area, and wherein the transmission schedule includesoverlapping scheduling for two or more anchor pairs of the anchor pairs.2. The device of claim 1, wherein the demarcated area comprises aplurality of regions, wherein the determining the anchor pairs and theidentifying the transmission schedule include, for each region of theplurality of regions, determining anchor pairs in that region andidentifying a transmission schedule for the anchor pairs in that region.3. The device of claim 1, wherein the overlapping scheduling comprisesscheduling of simultaneous wireless communications for the two or moreanchor pairs during a same time slot.
 4. The device of claim 1, whereinthe mobile device is configured to identify historical locations of themobile device in the demarcated area and determine, based on thehistorical locations, whether the mobile device is positioned in thefirst type of area such that the time difference of arrival measurementtechnique is to be employed for determining the mobile device locationor whether the mobile device is positioned in the different type of areasuch that the time of arrival measurement technique is to be employedfor determining the mobile device location.
 5. The device of claim 4,wherein the certain wireless signals each further includes dataregarding a location of at least one of the anchor pairs, a distancebetween the anchor pairs, a period of time for a first anchor of theanchor pairs to respond to a wireless signal transmitted by a secondanchor of the anchor pairs, or a combination thereof.
 6. The device ofclaim 1, wherein the operations further comprise receiving the mobiledevice location from the mobile device and tracking positioning of themobile device within the demarcated area according to the mobile devicelocation.
 7. The device of claim 1, wherein the operations furthercomprise obtaining additional mobile device locations for other mobiledevices, and mitigating a collision between at least two mobile devicesof the mobile device and the other mobile devices based on the mobiledevice location and the additional mobile device locations.
 8. Thedevice of claim 7, wherein the mitigating the collision between the atleast two mobile devices comprises controlling a motion of at least oneof the at least two mobile devices, initiating an alarm at or near theat least one of the at least two mobile devices, or a combinationthereof.
 9. The device of claim 1, wherein the transmission schedule fora respective anchor pair of the anchor pairs comprises an arrangement oftime slots individually assigned to that respective anchor pair.
 10. Thedevice of claim 9, wherein anchors of the respective anchor pair areconfigured to exchange wireless signals in a shared frequency bandduring the individually assigned time slots.
 11. The device of claim 1,wherein the mobile device location is determined by the mobile deviceresponsive to receiving a respective wireless signal from at least oneanchor of the anchor pairs.
 12. The device of claim 1, wherein theplurality of anchors is distributed in first regions of the demarcatedarea that include open spaces and second regions of the demarcated areathat include aisles.
 13. The device of claim 1, wherein the determiningthe anchor pairs comprises determining anchor pairs for a plurality ofmobile devices within the demarcated area.
 14. The device of claim 1,wherein the respective wireless signals correspond to ultra-widebandwireless signals.
 15. The device of claim 1, wherein the determining theanchor pairs comprises determining at least three anchor pairs from theplurality of anchors, and wherein the determination of the mobile devicelocation involves solving hyperbolic equations relating to the at leastthree anchor pairs.
 16. A non-transitory machine-readable mediumcomprising executable instructions that, when executed by a processingsystem including a processor, facilitate performance of operations, theoperations comprising: determining anchor pairs from a plurality ofanchors according to a location of each of the plurality of anchors,wherein each anchor pair of the anchor pairs has an overlapping coveragearea, resulting in overlapping coverage areas, and wherein thedetermining enables a determination of a mobile device location for amobile device relative to one or more of the anchor pairs within ademarcated area; and identifying, based on the overlapping coverageareas of the anchor pairs, a transmission schedule for the anchor pairsto transmit respective wireless signals for determining the mobiledevice location, wherein certain wireless signals of the respectivewireless signals each provides a respective identification of ameasurement technique that the mobile device is to employ for thatwireless signal for determining the mobile device location, wherein themeasurement technique comprises a time difference of arrival measurementtechnique when an anchor corresponding to the respective identificationis located in a first type of area within the demarcated area and a timeof arrival measurement technique when an anchor corresponding to therespective identification is located in a different type of area withinthe demarcated area, and wherein the transmission schedule includesoverlapping scheduling for two or more anchor pairs of the anchor pairs.17. The non-transitory machine-readable medium of claim 16, wherein theplurality of anchors is distributed in first regions of the demarcatedarea that include open spaces and second regions of the demarcated areathat include aisles.
 18. A method, comprising: determining, by aprocessing system including a processor, device pairs from a pluralityof devices according to a location of each of the plurality of devices,wherein each device pair of the device pairs has an overlapping coveragearea, resulting in overlapping coverage areas, and wherein thedetermining enables a determination of a mobile device location for amobile device relative to one or more of the device pairs within ademarcated area; and identifying, by the processing system and based onthe overlapping coverage areas of the device pairs, a transmissionschedule for the device pairs to transmit wireless signals, whereincertain wireless signals of the wireless signals each provides arespective identification of a measurement technique that the mobiledevice is to employ for that wireless signal for determining the mobiledevice location, wherein the measurement technique comprises a timedifference of arrival measurement technique when a device correspondingto the respective identification is located in a first type of areawithin the demarcated area and a time of arrival measurement techniquewhen a device corresponding to the respective identification is locatedin a different type of area within the demarcated area, and wherein thetransmission schedule includes overlapping scheduling for two or moredevice pairs of the device pairs.
 19. The method of claim 18, whereineach device of the plurality of devices comprises an anchor, and whereinthe plurality of devices is distributed in first regions of thedemarcated area that include open spaces and second regions of thedemarcated area that include aisles.
 20. The method of claim 18, furthercomprising tracking positioning of the mobile device within thedemarcated area according to the mobile device location.